Process for obtaining mineral oils with improved resistance to oxidation



United States Patent Ofifice 3,313,799 Patented. May 9, 1967 5 Claims. (Cl. 208-14) The invention relates to mineral oil compositions, and processes for producing such compositions, for various purposes such as industrial oils, engine oils and insulating oils, having among other advantageous properties that of outstanding oxidation resistance.

These oils are generally prepared from distillates or deasphalted residues according to various refining processes, according to their origin, e.g. treatment by a selective solvent such as phenol or sulfur dioxide, so as to eliminate aromatics of low viscosity index, dewaxing, acid or oleum treatment, treatment with activated earth, or hydrogenation to improve colour and stability.

According to the present invention, a mineral oil composition comprises a major proportion of a mineral base oil and from 0.1 to by weight, in relation to the base oil, of a heavy cycle gas oil fraction obtained in the catalytic cracking of a petroleum fraction.

Also according to the invention, a process for producing a mineral oil composition comprises adding to a mineral base oil from 0.1 to 10% by weight, in relation to the base oil, of a heavy cycle gas oil fraction obtained in the catalytic cracking of a petroleum fraction.

The heavy cycle gas oil fraction is obtained in the refinery in cracking operations, for instance in those of catalytic cracking according to the process known in the trade by the name of Fluid Catalytic Cracking. In these operations, at the same time as the light products form, there are formed heavy fractions known in the trade as light cycle gas oil and heavy cycle gas oil. These fractions are very rich in aromatics and very stable thermally. As a rule they are recycled to the feed of the catlytic cracking plant after distillation, or are used for miscellaneous purposes, such as the manufacture of carbon black.

The heavy cycle gas oil fraction (hereinafter referred to as HCGO) has variable characteristics, according to the regulation of the catalytic cracking unit and the way in which it is separated by distillation from the other products produced by cracking. These characteristics are in general comprised within the following limits:

Density at 15 C. (59 F.) g./cc 0.990 to 1.100 Viscosity at 98.9 C. (210 F.) centistokes 2-8 Aniline point C to 80 Distillation range C between 180 and 660 1 Temperatures under atmospheric pressure.

can be obtained by conventional dewaxing with a yield of, for example, 85%.

The dewaxing treatment in no Way modifies the other properties conferred on the final oil by the HCGO, in particular from the point of view of resistance to oxidation.

In order to increase the aromatic content of the HCGO, it may be subjected, whether or not dewaxed, before addition to the base oil, to refining by treatment with selective solvent (phenol for instance), e.g. so as to obtain an extract yield of 80 to 95%, preferably to Preferably, also, the HCGO is subjected, whether or not dewaxed or treated with a selective solvent, prior to its addition to the base oil, to a light acid treatment, eg treatment with 5% to 20%, preferably 8 to 12%, by weight of 98% sulphuric acid. The acid tars are then separated, e.g. by decanting in the hot state (80 to 100 C.) and. the acid raffiuate is neutralised, e.g. with an aqueous or alcoholic solution of soda or potash, which neutralisation is followed by washing with water and drying, e.g. on natural earth (silico-aluminate).

The HCGO, as such or after it has undergone one or more of the treatments mentioned above may be'added to the base, preferably after the latter has been treated with a selective solvent to reduce its aromatic content, and as a rule before the finishing treatment, such as treatment with natural or activated earth or, preferably, treatment with hydrogen.

Alternatively, the base oil and the HCG'O, as such or after it has undergone one or more of the treatments mentioned above, are mixed after subjecting the oil and the HCGO separately to such finishing treatment.

The quantity of HCGO used, whether treated or not, is preferably 1 to 5%, by weight in relation to the base oil.

The following examples will better show the scope and importance of the invention.

Example I The starting material was an HCGO derived from a catalytic cracking unit known as Fluid Catalytic Cracking" and having viscosity at 989 C. (210 of 2 centistokes.

From this HCGO there were prepared several different products by proceeding as follows:

(A) Product A.Obtained by distillation under reduced pressure as the 60100% fraction which distills over from 420 to 600 C. (temperatures under atmospheric pres"- sure).

(B) Product B.-Obtained by distillation under reduced pressure as the 40100% fraction which distiils over from 350 to 600 C. (temperatures reduced to atmospheric pressure).

(A1) Extract of, product A .-Separated from product A by treating it with excess of phenol (100% phenol and 5% water in relation to the product A) at 55 C. There were thus obtained 5% rafiinate and 95% extract, after distilling off the phenol in both phases.

(A2) Extract of product A treated with acid.-Obtained by treating (A1) with 10% of 98% sulphuric acid, decanting the acid tars at 90 C., neutralising the acid rafiinate with aqueous caustic soda solution, washing with water and drying on natural earth (yield 70% in relation to the amount of (A1) used).

(B1) Product B treated with acid.-Obtained by treating (B) with acid in the same conditions as for (A2). (Yield 70% in relation to the amount of (B) used.)

These different products had the following characteristics:

oxidation, and to obtain insulating oils of excellent quality.

Product A A1 A2 B B1 Density at 15 C. (g./cc.) 1. 030 1. 092 1.078 0. 999 O. 980

Viscosity at 989 0. (210 F.) (centist0kes) 7. 4 6. 5 5.80 5. 4

Flash point, open vessel C.) 226 226 228 210 220 Aniline Point C.) 79. 8 31 33. 6 72 75. 2

Refractive index at 70 0 1. 5083 1. 0480 1. 6330 1. 5760 1. 5605 Mean molecular weight.... 350 280 220 321 325 By using these different products, different insulating Example II oils were prepared starting from a light raffinate obtained by refining with phenol a light Tia Juana distillate, this being done so as to obtain a rafiinate having a VGC (viscosity gravity constant) of 0.822 (rafiinate yield 55%).

The oils consisting of the rafiinate as such and the raflinate with the addition of the different products in question were submitted to a finishing treatment consisting of light hydrogenation performed under the following conditions:

Temperature: 280 C. Pressure: 60 atm.

volume oil/hour Spatial speed (volume y 1v./v./h.

pressure temperature) hour Flow mtlo volume oil/hour Catalyst: Cobalt molybdate on alumina (3.5% C00 and To appreciate the resistance to oxidation of these insulating oils the following tests were performed:

(1) The so-called B.B.C. test, which consists of heating to 110 C., 1000 cc. of the oil in a copper pot, in the presence of a cotton thread. After 72 hours and after 16 8 hours, the NPA colour (ASTM D. 155) and the acid number (ASTM D. 947) of the oil are determined, as well as the quantity of deposits and the percentage loss of strength of the cotton thread. After 168 hours a measurement is also made of the dielectric loss i.e. the tangent of the angle of loss, of the oxidised oil.

(2) The so-called C.E.I. test, which consists of bubbling oxygen at 100 C., with a delivery of 1 litre/hour, through g. oil in a glass tube in the presence of a copper wire. After 164 hours the quantity of deposits and the acid number of the oxidised oil are measured. These tests furnished the following results:

Volume hydrogen (under normal) The starting material was an HCGO derived from a catalytic cracking unit known as Fluid catalytic cracking and having a viscosity at 989 C. (210 F.) of 3.88 centistokes. From this HCGO (C) the following different products were prepared:

(Cl) Dewaxed product.-Obtained by dewaxing HCGO (C) by cooling to 25 C. and filtering a solution comprising 1 part (by volume) of HCGO (C) and 3 parts (by volume) secondary butyl acetate, with a yield of 85%.

(C2) Dewaxed product treated with acid.-Obtained by treating (C1) with 10% of 98% sulphuric acid, decanting the acid tars at 90 C., neutralising the acid raffinate with an aqueous caustic soda solution, washing with water and drying on natural earth (yield 75% in relation to the (C1) used).

These different products had the following characteristics:

Product C 01 02 Density at 15 C. (g./cc.) 1. 000 1.010 1. 015 Viscosity at 980 0. (210 F.) (centistokcs) 3. 88 4.05 3. 93 Flash point (open cup) C.) 174 174 178 Aniline point C 56. 6 46. 8 45. 8 Pour point ASTM D97-47 O.) 3 -11 Refractive index at C 1. 5820 Mean molecular weight percent arom 265 bon (infrared method) 01. 69.0 64. 5 Percent Sulphur 2. 23 2. 48 2. 55 Percent Nitrogen 0. 095 0. 117 0. 005

Using the dewaxed product (C1) and the acid-treated dewaxed product (C2), insulating oils were prepared from a basic oil consisting of the same light raftinate as in Example I.

The oils, consisting of the light rafiinate as such and with the addition of the products in question, were submitted to a finishing treatment consisting of hydrogena- Additive None 2% A1 2% A2 2% B 2% B1 4% A1 4% A2 4% B 4% B1 NPA Colour- 1% 1% 2'- 1 Acid index (mg. KOH/g.) 0. 098 0. 042 0.028 0.042 0.028 O. 042 0. 028 0. 028 0. 028 Deposits (g.) 0. 008 Traces 0 0 0 O. 006 Traces 0 0 Percent loss of strength of cotton thread 0 0 2 0 3 0 0 0 After 168 h.:

NPA 0 ur 4+ 3 3%- 3%+ 3- 4- 3 2%- 3- Acid index (mg. KOH/g 0. 224 0. 070 0. 084 0. 098 0. 098 0. 070 0. 0 8 0. 042 0. 084 Deposits g.) 0. 055 0. 010 0. 015 0. 018 0. 030 0. 017 0. 013 0. 013 0. 011 Percent loss of strength of cotton thread 10 20 15 10 23 13 7 4 10 Tangent of angle of loss 0.2750 0. 0200 0. 0240 0. 0240 0.0220 0. 0145 0 0092 0. 0085 0. 0180 C.E.I. Test:

Acid index (mg. KOH/g.) 0.220 Traces 0. 056 0.056 0.022 Traces 0. 056 Traces Traces Deposits (g.) 0. 020 0. 009 0. 006 0. 012 0. 005 0. 013 0. 015 0. 006 0. 005

These results show that the addition of a small quantity of HCGO, treated or not with acid, or an extract of this fraction treated or not with acid, to a light raflinate prior to hydrogenation makes it possible to improve very contion performed under the same conditions as in Example I.

To appreciate the resistance to oxidation of these insiderably its properties, in particular its resistance to 75 sulating oils, the BBC. and C.E.I. tests described in Example I Were effected, which tests furnished the following results:

Additive N one 4% Cl 4% C2 B.B.O. Test:

After 72 h.:

NPA Colour 3 2 2 Acid index (mg. KOH/g.) 0. 098 0. 042 0. 042 Deposits (55.) 0.008 Traces Traces Percent loss of strength of cotton thread 0 0 After 168 h..

NIA Colour 4+ 3 3% Acid index (mg. KOH/g.) 0. 224 0. 084 0. 100 Depositsc 0. 055 0. 023 O. 018 Percent loss of strength of cotton thread 10 20 20 Tangent of angle of loss 0.2750 0. 0418 0.0650 C.E.I. Test:

Acid index (mg. KOH/g.) 0.220 0. 056 O. 022 Deposits (g.) 0.020 0. 010 0. 008

What is claimed is:

1. An insulating oil composition consisting essentially of a major amount of a mineral base oil of a type normally used in insulating oil compositions but deficient in oxidation resistance, and as an oxidation resistance improver about 1 to 5 wt. percent of a hydrogenated heavy cycle gas oil fraction obtained by catalytic cracking and having a density at 59 F. in the range of 0.990 to 1.100 g./cc., a viscosity at 210 F. in the range of 2 to 8 centistokes, an aniline point in the range of 25 to 80 C. and a distillation range under atmospheric pressure between about 180 C. and 660 C.

2. A composition according to claim 1, wherein said gas oil fraction before hydrogenation has been treated with concentrated sulfuric acid, the acid tars formed thereby have been removed, the rafiinate resulting from said treatment has been neutralized and then washed 6 with water, after which the rafiinate has been dried am hydrogenated to thereby form said improver.

3. A composition according to claim 2, wherein sair oil fraction is dewaxed before said treatment with so] furic acid.

4. A composition according to claim 1, wherein sail base oil and said heavy gas oil fraction are hydrogenater while mixed together.

5. A process for preparing a heavy cycle gas oil frac tion as an oxidation inhibitor wherein said heavy cyclr gas oil fraction is obtained in the catalytic cracking o: a petroleum fraction, has a density of 59 F. in the range of 0.990 to 1.100 g./cc., a viscosity at 210 F. in the range of 2 to 8 centistokes, an aniline point in the range of 25 to C. and a distillation range under atmospheric pressure between about 350 C. and 660 C. which comprises dewaxing said fraction, treating saiC dewaxed fraction with concentrated sulfuric acid, removing the acid tars formed thereby, neutralizing the rafiinate resulting therefrom, washing said rafiinate with water, drying the washed raflinate and then treating with hydrogen.

References Cited by the Examiner UNITED STATES PATENTS 2,660,552 11/1953 Blanding 208--24 2,846,372 8/1958 Schneider et a1. 20 8-l4 3,000,807 9/1961 Wasson et ai. 208-l4 3,095,366 6/1963 Schieman 20814 3,192,153 6/1965 Smilski 208-264 3,196,102 7/1965 Mills et al. 208-14 DANIEL E. WYMAN, Primary Examiner. P. E. KONOPKA, Assistant Examiner. 

1. AN INSULATING OIL COMPOSITION CONSISTING ESSENTIALLY OF A MAJOR AMOUNT OF A MINERAL BASE OIL OF A TYPE NORMALLY USED IN INSULATING OIL COMPOSITIONS BUT DEFICIENT IN OXIDATION RESISTNACE, AND AS AN OXIDATION RESISTANCE IMPROVER ABOUT 1 TO 5 WT. PERCENT OF A HYDROGENATED HEAVY CYCLE GAS OIL FRACTION OBTAINED BY CATALYTIC CRACKING AND HAVING A DENSITY AT 59*F. IN THE RANGE OF 0.990 TO 1.100 G./CC., A VISCOSITY AT 210*F. IN THE RANGE OF 2 TO 8 CENTISTOKES, AN ANILINE POINT IN THE RANGE OF 25* TO 80*C. AND A DISTILLATION RANGE UNDER ATMOSPHERE PRESSURE BETWEEN ABOUT 180*C. AND 660*C. 